Method of recovering and regenerating waste gas desulfurizing and defluorinating absorbent liquid continuously

Abstract

The method of recovering and regenerating waste gas desulfurizing and defluorinating absorbent liquid continuously includes absorbing SO2 and / or fluoride from waste gas with alkaline absorbent to generate desulfurizing and defluorinating absorbent liquid containing sodium sulfite, sodium bisulfite and / or fluoride; the subsequent reacting the desulfurizing and defluorinating absorbent liquid with magnesium-base suspension or solid to obtain magnesium sulfite and / or magnesium fluoride precipitate; filtering to eliminate magnesium sulfite and / or magnesium fluoride precipitate, and recovering the filtrate at pH 6.5-9.5 for reuse. The said method has fast regeneration reaction speed, low cost and complete reaction.

Description

technical field [0001] The invention relates to a method for defluorinating waste gas containing fluorine and sulfur and recovering and regenerating the desulfurization absorption liquid. Background technique [0002] At present, the industrial waste gas containing sulfur and fluorine is mainly concentrated in the waste gas of power plant boilers, glass melting furnaces and glass fiber pool kilns. These waste gases mainly contain harmful components such as sulfur dioxide and fluoride, which are harmful to the environment. There are many researches on the technology of removing sulfur dioxide at home and abroad, and there are single-component and double-component desulfurizers. [0003] The specific methods of single-component treatment are as follows: 1. Ammonia water as absorbent: spray to absorb sulfur dioxide in the exhaust gas, and the ammonium bisulfite generated is treated with ammonia to obtain ammonium sulfite, which is oxidized to produce ammonium sulfate as a by-pr...

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Problems solved by technology

[0003] The specific methods of single-component treatment are as follows: 1. Ammonia water as absorbent: spray to absorb sulfur dioxide in the exhaust gas, and the ammonium bisulfite generated is treated with ammonia to obtain ammonium sulfite, which is oxidized to produce ammonium sulfate as a by-product , this method has been introduced in ZL98117223.7, but this method ammonia is easy to volatilize, causes new pollution; Two, calcium-alkaline method: use the suspension of lime or calcium hydroxide as absorbent to absorb sulfur dioxide in the flue gas, Calcium sulfite is generated, and gypsum is oxidized as a by-product. This method has a huge absorption system equipment, a large circulation of lime milk, and the system is easy to scale and block, but it is still widely used in industry; 3. Sodium-alkali method: use sodium hydroxide or sodium carbonate Aqueous solution is used as absorbent. This method has simple equipment and low investment, but it consumes a lot of alkali and costs high, so it is rarely used in production.

4. Magnesia lime method: use magnesium lime water slurry (13-20%) to absorb sulfur dioxide in flue gas. Due to the use of slurry, storage and transportation are difficult in this method, and the system is prone to fouling and blockage

The specific methods are as follows: 1. Use ammonia as desulfurizing agent and calcium hydroxide as desulfurizing regenerating agent. This method is introduced in ZL97103626.8. This method is easy to volatilize ammonia, causing new pollution, and the regeneration reaction speed is relatively slow; 2. 1. Using magnesium base as desulfurizer, lime or calcium hydroxide as regeneration agent, calcium sulfite oxide to make by-product gypsum, this method has been introduced in ZL95104688.8, ZL02146547.9, ZL02806288.4, etc. The solubility of magnesium sulfite is small, and the amount of magnesium sulfite in the absorption liquid is relatively small, so that the volume of circulation absorption liquid is large, the energy consumption is increased, and the regeneration speed of calcium hydroxide is slow, and the regeneration device is huge

The by-product calcium sulfate has no utilization value

3. Use sodium base as desulfurizer, lime or calcium hydroxide as regenerant, and oxidize calcium sulfite to make by-product gypsum. He Zhensheng and others introduced it in the third issue of "Glass Fiber" in 2004, and ZL01107106.0 also made an introduction It has been introduced that the regeneration reaction time of this method is long, the regeneration device is huge, and the reaction is incomplete, resulting in a large amount of alkali consumption and high operating costs, so it is rarely used in large-scale industrial devices.

4. Magnesium sulfite circulation method: use magnesium sulfite clear liquid to circulate and absorb sulfur dioxide in the flue gas, the generated magnesium bisulfite reacts with magnesium hydroxide to form magnesium sulfite, and the saturated magnesium sulfite clear liquid returns to the absorption unit. The solubility of magnesium sulfite in water is low, the circulation of clear liquid is large, the pH of the absorption liquid at the inlet and outlet of the absorption tower changes greatly, which affects the absorption efficiency, and the absorption unit equipment is relatively large

At present, the main method for treating the waste gas produced by glass melting furnaces and glass fiber tank kilns is the sodium-calcium method. The waste gas contains sulfur dioxide and fluoride. The sodium-calcium method uses sodium base as a desulfurizer, and sodium hydroxide reacts with sulfur dioxide and fluoride , to generate sulfite and fluoride; lime or calcium hydroxide is used as the regeneration agent to generate calcium sulfite and fluoride salt precipitation, and the regeneration solution sodium sulfite and sodium hydroxide aqueous solution go back to absorb sulfur dioxide and fluoride. This method regenerates the reaction The time is long, the regeneration device is huge, the reaction is not complete, the fluoride is accumulated in the circulating fluid, and the consumption of alkali is large, and the operating cost is high

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